Production of colored photographic images by color development and composition therefor



Patented Feb. 23, 1943 UNITED STATES PATENT OFFICE PRODUCTION OF COLORED PHOTOGRAPHIC IIVIAGES BY COLOR DEVELOPMENT AND COMPOSITION THEREFOR John David Kendall and Ronald Bernard Collins,

Ill'ord, England, assignors to lliord Limited, Ili'ord, Essex, England, a company of Great Britain No Drawing. Application July 20, 1939, Serial No. 285,590. In Great Britain July 22, 1938 12 Claims. (Cl. 95-6) compounds. A further object is the provision of new photographic color developing processes.

A still further object is the preparation of photographic elements bearing emulsions which contain color formers which do not migrate and in particular the preparation oi multilayer photographic film containing color formers which do not migrate from layer to layer or into the processing baths. A still further object is the preparation of finished photographs which contain stable dyed images which are formed of waterinsoluble dyes. Still other objects will appear hereinafter. v

The above and other objects are accomplished by the following invention which involves the preparation and use of new organic compounds oi .the general iormula:

developer or the emulsion. The colored image thus produced may be revealed by dissolving out the silver. image with the aid of Farmer's reducer or other known suitable silver solvents.

- It has been discovered that compounds of the above general formula are especially valuable color-formers in this connection and according to one embodiment of this invention, colored photographic images are produced by developing silver halide photographic emulsions in which a latent image has been formed with an aromatic l-amino-. compound as the developing ag'entin the where X a cyano, -carboxylic acyl or esterfied carboxyl group and-fl; is an of a color former of the general for- 'cleus having an alkyl radical attached to a heterocyclic nitrogen atom. Examples of suitable heterocyclic nuclei are substituted and unsubstituted thiazoles, thiazolines, oxazoles, oxazolines, selenazoles, selenazolines, pyridines, quinolin'es, indolenines, diazoles and diazines (as described in British Specification No. 425,609), e. g. pyrimidines, thiodiazoles and quinazollnes. Substituted nuclei include polycyclic compounds such as benzthiazoles, naphthathiazoles and anthrathiazoles and substituent groups which may be present in these nuclei include alkyl, aralkyl, aryl, amino, substituted amino, hydroxy, alkoxy, aryloxy, nitro and halogen groups.

Where X in the above formula is an esteriied carboxyl group. i. e. where the color former has the formula:

the group B may be any hydrocarbon or substituted hydrocarbon radicle. Thus It may be an alkyl group, e. g. a methyl, ethyl, propyl, butyl of higher alkyl group, an aryl group, e. g., aphenyl or naphthyl group. an aralkyl group, e. g. a ben zyl group or a cyclo-aliphatic group, e. g. a cyclohexyl group.

The new color formers may be produced in various ways. For example, suitable heterocyclic compounds containing one or more cyclic nitrogen atoms and substituted in the on position in the case of a five-membered ring (e. g. thiazoles) or in the a or '7 position in the case of a six membered ring (e. g. quinolines) by an imino group may be condensed with compounds of the type ACOCHi-X where X has the meaning assigned to it above or is a group which is readily replaceable by or convertible into a cyano group,

i a carboxylic acyl group or an esterfied carboxyl group, and A is a group such as a hydroxy, alkoxy or amino group or a halogen atom capable of combining with the hydrogen of the imino group to form a compound which is split on! under the reaction conditions. Thus, where A is an alkoxy group, an alcohol is split oil by the condensation and no condensing agent is in general necessary. Where A is an amino group, ammonia or an amine is split on and an acid condensing agent is useful, e. g. hydrochloric acid or acetic acid; Where A is a' halogen atom, an acid is split oil, and an alkaline condensingagent is useful, e. 8. sodium acetate, sodium carbonate, piperidine or pyridine.

According to another method of preparation,

suitable heterocyclic compounds containing one N-heterocyclic nuo5 vor more cyclic nitrogen ,atoms, and substituted 1 in the a position in the case of a five membered ring or-in the on !.7 positions in the case of a six membered ring by an amino group may be condensed in the form of their alkyl salts with compounds of the type ACO--CHz--X as defined in the preceding paragraph. The condensation in this case proceeds according to the general equation:

D in the above equation represents the residue oi. a heterocyclic nucleus, R is an alkyl radical and Z represents the residue of an acid. A condensing agent may be employed, e. g. pyridine or other alkaline condensing agent.

The color formers according to the invention may be incorporated in the silver halide emulsion which is to be developed or they may be added to the developer solution. They are very insoluble in water and have little tendency to diffuse from one layer to another when incorporated in the emulsion layers of multi-layered material. The compounds in which X in the foregoing formula is a carboxylic acyl group are particularly valuable where yellow colors are desired and the others are especially valuable where red colors are desired.

Suitable aromatic amino compounds which may be employed as developers in conjunction with the color formers of this invention are derivatives of p-phenylene diamine and particularlythe asymmetric dialkyl-p-phenylene diamines, e. g. p-aminodimethylaniline, p-aminodiethylaniline and p aminodibutyl aniline. Other developing agents which may be used include p-phenylene diamine itself, p-methylaminoaniline,p-ethylaminoaniline and p-aminophenol, N.N-diethyl-pphenylene diamine, chloro-p-phenylene diamine, 1.2.5-toluylenediamine, 2-amino-5-diethylaminotoluene, N p aminophenolpiperidine, N-methyl-N-hydroxyethyl pphenylenediamine, N-butyl-N-hydroxyethyl-pphenylenediamine, 2-amino-5-(N-p-hydroxyeth .yl-N-butyl) amino toluene and a-7-dihYd10XY- propyl-p-phenylene diamine. These compounds may also be used in the the form of their salts which may be either inorganic or organic, the salts being in general more stable than the free bases. Examples oif suitable salts are the hydrochlorides, sulphates and acetates.

In the succeeding examples, the following solution is given by way of example as illustrating The color former is dissolved in a suitable watermiscible solvent such as ethyl alcohol or ethylene glycol mono methyl ether.

The sodium sulphite may be omitted if desired. The following examples illustrate the method of production of the new color formers, and their use:

EXAMPLE I 1-w-acetoacetylimino-2-methyl-dihydrobenzthiazole s 3.28 gms. of 1-imino-2-methyl benzthiazole and 2.6 gms. of acetoacetic ethyl ester were heat-.

EXAMPLE Ll? 1-cyanacetylimino-2-methyldihydrothiazole 1.14 gms. of 1-imino-2-methyl thiazole and 1.13 gms. ethyl cyanacetate were heated together the nature of developing solutions which may employed embodying a color former in accordance with the invention.

DEVELOPING SOLUTION A Diethyl-p-phenylene diamine hydrochloride gm 1 Sodium carbonate (crystals) NazCOalOHzo gms 80 Sodium sulphite (crystals) NazSO37H2O gms 12.5 Color former solution (1% or saturated solution whichever is weaker) ccs 100 Water to make litre 1 in an oil bath at -150 C. for 1 hours. On cooling, a brown solid separated: this was collected, washed with ether andethyl alcohol, leaving a white solid, M. P. 195 0'.

Developing solution A when including this compound and used for the development of photographic silver halide'emulsions produced a red image together with the silver image.

EXAMPLE III 1-w-fur0yl-acetylimino-2-ethyldihydrobenzthiazole 1.78 gms. of 1-imino-2-ethyl benzthiazole and 1.82 gms. of ethyl furoylacetate were heated together in an oil bath to 178 C. for a short time to initiate reaction and then maintained at C. for 20 minutes. On cooling, an oil remained which gave a yellow solid on' trituration with ethyl alcohol. After recrystallisation from ethyl alcohol, 2.07 gms. of yellow crystals, M. P. 140 C. were obtained. Developing solution A when including this compound and used for the development of photographic silver halide emulsions produced a yellow image together with. the silver image.

Other hetrocyclic carboxylic acyl acetic esters.

aeraoao e. g. esters containing the acyl radicles'corre- .sponding to nicotinic, picolinic and isonicotinic acids and thienyl carboxylic acids may be sub stituted in like amounts.

Exmu: IV 1 methyl -2w-cyanacetyliminodihydroquinoline 1.94. gms. of l-amino-i-ethomhenzthiazole and 1.86 gms. of methyl-p-toluene sulphonate were mixed together and fused in an oil-bath at 10-140'C. for three hours. 1.13 gms. of ethylcyanacetate were then added .1 and the mixture fused in an oil-bath at 150-160 C. for one hour.

' cos. of pyridine and 5 drops of diethylamine 0.78 gm. of l-methyl-Z-imino quinoline and EXAMPLE V 1-ethylmalonylimino-Z-methylbenzthiazole 3.28 gms. of l-imino-2-methylbenzthiazole and 3.2 ms. of ethyl malonate were heated together in an oil bath at 150 C. After three quarters of an hour the temperature was raised slightly when reaction commenced and the products set solid. The mixture was then boiled out with 50 cos. of .dry alcohol and filtered hot.

The filtrate deposited white crystals. The crystalline product when included in Developing solution A and used for the development of photographic silver halide emulsions produced a red. image together with the silver image.

ExAuPLr. VI 1 -cyanacetylimino-2-methz lbenzthia20le .quantities 2 gms. of phosphorus pentachloride.

The mixture was allowed to stand for 4 hour and' poured into ice water. The solid product separated out. when included inDeveloping solution A and used for development of. silver halide photographic emulsions it produced a red image together with the silver image.

Exnnm: VII 1 -w-cyandcetylimino-Z-methfll-S-ethOmydihydrobenzthiazole were then added and the mixture boiled for one hour. Oncooling a yellow solid separated. This product, whenadded to Developing solution A and used for the development of photographic silver halide emulsions, produced a ed image, together with the silver image.

EXAMPLE VIII 1 JuroylacetyliminmZ-methyZdihydmbenz thiazole 1.5 gms'. of l-aminobenzthiazole and 1.86 gms. I

of methyl-p-toluene sulphonate were mixed together and fused in an oil-bath at -140 C, for three hours. The mixture was then'dissolved'in 30 cos. of water, cooled to 0 C. and rendered alkaline by the addition of 5 cos. of aqueous sodium carbonate.

An oil separated which was extracted with 50 cos. of ether; the ether extract was dried over potassium carbonate and the ether removed. The residual oil was dissolved in 10 cos. of dry xylene and slowly run into 2000s. of a looiling' xylene solution containing 2 gms. ethyl-u-furoyl acetate and 3 drops of pyridine. The mixture was then refluxed for /4 hour and the xylene removed until only 10 cos. remained. This residual solution was cooled in a freezing mixture whereupon a solid separated, having melting point 176-177" C. This solid, when included in Developing solution A and used for the development of silver halide photographic emulsions, produced a yellow image together with the silver image.

In this preparation the intermediate compound l-w-chlor actyl imino-2-ethylbenzthiazoleis first prepared and this is then converted to the cor-' responding cyano compound. The intermediate l-w-oh1oracetylimino-2-ethylbenzthiazole. may be prepared by any of the following three methods:

'(a) 1.78 gms. of, 1-imino-2-ethylbenzthiazole was dissolved in 10 cos. of pyridine and there was added to the mixture, drop by drop, with stirring, 1.13 gms. of chloraoetyl chloride. The mixture fumed vigorously and pyridine hydrochloride separated. The mixture was poured into water when the pyridine hydrochloride redissolved and the solid product was precipitated, having a melting pointof 136 C.

(b) 1.5 gms. of l-aminobenzthiazole'and l gms. of ethyl-p-toluene sulphonate were mixed together and fused at 140-150" C. for three hours. The mixture was dissolved in 20 cos. of pyridine, cooled to 0 C. and there was then added, with stirring, 1.13 gms. of chloracetyl chloride. The mixture was then warmed on a water bath for half an hour with. occasional shaking and was then poured into water whereupon the solid product separated.

(c) 1.78 gms. of 1-imino-Z-ethyI-dihydrobenzthiazole, 0.94 gm. of chloracetamide and 10 cos. of glacial acetic acid were mixed together, warmed on a water bath for half an hour and then gently refluxed for one hour. The mixture was then poured into water, whereupon the solid product separated.

0.5 gm, of 1-w-chloracetylimino-2-ethylbenzthiazole prepared by any of the above three methods were dissolved in 10 cos. of ethyl alcohol and the solution slowly added to a. hot solution of 0.5 m. of potassium cyanide dissolved in 5 cos. of water. The mixture was then boiled on a water bath for 1-2 hours, cooled and the solid product which separated removed by filtration.-

The solid product was then washed and crystallised from cos. of ethyl alcohol. It has a melting point of 130 C. This solid product when included in Developing solution A and used for the developing of photographic silver halide emulsions produced a red image together with the silver image.

EXAMPLE X This example illustrates the incorporation of the color formers of this invention in emulsion layers. cos. of a 1% solution in ethylene glycol monomethyl ether of l-w-acetoacetylimino-2-methyl dihydrobenzthiazole were added to cos. of a 10% aqueous solution of gelatin and the mixture added to 50 cos. of a melted photographic Gaslight emulsion containing approximately 20 gms. of silver halide, chiefly silver chloride, per pound weight of emulsion. The emulsion thus prepared was coated on a paper support and dried. The emulsion coated paper was exposed under a negative and was then developed with a Developing solution A excluding the color former but including an equivalent quantity of the water miscible liquid such as ethylene glycol mono methyl ether. A yellow image was produced together with the silver image.

In addition to the specific color formers described in the Ioregoing examples the following are also examples of representative color formers which may be prepared and used according to the invention:

l-w-acetoacetylimino-2-ethyldihydrobenzthiazole 1-w-ethylmalonylimino-2 ethyldihydrobenzthiazole l-w-benzoylacetylimino-2- ethyldihydrobenzthiazole 1-w-acetoacetylimino-2- methyl 5 ethoxydihydrobenzthiazole l-methyl-Z-w-cyanacetyliminodihydropyridine 1-ethyl-2-w-cyanacetyliminodihydroquinoline 1-w-cyanacetylimino-2-methyl-3-phenyldihydrothiazole l-w-furoylacetylimino-Z-methyl 3 phenyldihydrothiazole i '1-w-cyanacetylimino-2- methyldihydrobenzselenazole The process of development employing the color formers in accordance with the present invention may be applied either to a latent image in an emulsion of a silver halide which has been exposed to the action of light, for example. in a camera/or behind a photographic negative image; or it may be applied to the residual silver halide left when an initial reduced silver image has been dissolved away as in the reversal process of development; or it may be applied to a developed photographic image in metallic silver which has been fixed by the removal of unchanged silver halide and subsequently converted to a developable silver salt by means of known photographic bleaching agents. In the last tWo cases the residual silver halide and the silver salt respectively may be made developable by the action of light or in any other way, e. g. by treatment with sodium arsenite.

The production of colored images by means of the color formers of this invention may be applied to colloid layers sensitised by bichromate. Thus the color formers may be incorporated in colloid layers (i. g. gelatin, gum arabic or albumin), the layers exposed, the unexposed colloid removed, e. g. by treatment with hot water, and the color developed in the exposed portions by treatment with p-nitroso-dialkyl-aniline or its derivatives.

The new compounds of this invention may be coupled with various diazo compounds toproduce azo dyestufi's, e. g. diazonium salts, syndiazotates, diazo-anhydrides, diazo inner salts of the formula PN=NQ where P is an aromatic or unsaturated heterocyclic residue and Q is a hydroxy group, a salt group such as ONa, or a salt forming anion, e. g. Cl, Br, Now and SOiH, and compounds resulting from intramolecular elimination of HQ therefrom.

The following example illustrates the production of an azo dyestuii by coupling one of the compounds of the present invention with a diazo compound:

EXAMPLE XI 0 M ethorybenzeneazo 1 acetoacetylimino 2- ethylbenzthiazole EH30 l C:\L|CHN==N- =0 7 1.23 gms. of o-anisidine were dissolved in 2 cos. of concentrated hydrochloric acid and 15 cos. of wat r. The solution was cooled to 0 C. and diazotized by the addition of a solution of 0.7 gm. sodium nitrite in 10 cos. of water. This solution was then immediately poured into a solution of 2.62 gms. l-acetoacetylimino-2- ethyl-dihydrobenzthiazole, dissolved in 50 ccs. of spirit and 20 cos. of 33% aqueous caustic soda solution, this solution having previously been cooled to 0" C. The solution became deep orange and a dark red solid separated. This solid was filtered ofi, washed 'with water and recrystallised from 50 cos. of ethyl alcohol. The product which has a melting point of 1l7119 C. gives an orange-yellow solution.

We claim:

1. A photographic color forming developer which comprises an aromatic amino developing compound containing an unsubstituted amino group and a color formerof the general formula:

Y=N COCH2-X' where X is a radical selected from the group COl'lSlStll'lg of the cyano group, carboxylic acyl and esterified carboxyl groups and Y is an N- heterocyclie nucleus containing an alkyl radical attached to a heterocyclic nitrogen atom which is attached to the acyclic nitrogen atom by the double bond by means of an intracyclic carbon atom, which is in a position taken from the group consisting of a and 7 positions to the N-hetero-' cyclic nitrogen atom.

2. A photographic color forming developer which comprises an asymmetrical di-alkyl-pphenylene diamine and a color former of the general formula:

where X is a radical selected from the group consisting of the cyano group, carboxylic acyl and esterifled carboxyl groups and Y is an N- heterocyclic nucleus containing an alkyl radical attached to a heterocyclic nitrogen atom which is attached to the acyclic nitrogen atom by the double bond by means of an intracyclic carbon atom which is in a position taken from the group consisting of a and 7 positions to the N-heterocyclic nitrogen atom.

3. A method of producing a colored image in a silver halide emulsion'which comprises developing the emulsion with an aromatic amino developing agent containing an unsubstituted amino group in the presence of a color former of the general formula: I

Y=NCQCHz-X' where X is a radical selected from the group consisting ,of the cyano group, carboxylic acyl and esterified carboxyl groups, and Y is an N- heterocyclic nucleus containing an alkyl radical attached to a heterocyclic nitrogen atom which is attached to the acyclic nitrogen atom by the double bond by means of an intracyclic carbon atom which is in a position taken from the group consisting of a and 7 positions to the N-heterocyclic nitrogen atom.

4. A method of producin-gfa colored image in a silver halide emulsion inwhich a silver image has been produced and the residual silver halide removed by fixing, which comprises convertin the silver image to a redevelopable silver salt and re-developlng with an aromatic amino compound containing an unsubstituted amino group in the presence of a-color former of the general formula: I

Y=NCOCHaX where X is a radical selected from the group consisting of the cyano group, carboxylic acyl and esterified carboxyl groups, and Y is an N- heterocyclic nucleus containing an alkyl radical attached to a heterocyclic nitrogen atom which is attached to the acyclic nitrogen atom by the double bond by means of an intracyclic carbon atom which is in a position taken from the group consisting of a and '7 positions to the N-heterocyclic nitrogen atom.

- 5. A light sensitive silver halide photographic emulsion containing a colofforr'ner of the generalformula:

. Y=NCOCH2-X where X is a radical selected from the group consisting oi. the cyano group, carboxylic acyl.

and esterifled carboxyl groups, and Y is an N- heterocyclic nucleus containing an alkyl radical attached to a heterocyclic nitrogen atom which is attached to the acyclic nitrogen'atom by the double bond by means of an intracyclic carbon atom which is in a position taken from the group consisting of a and 1 positions to the N-heterocyclic nitrogen atom.

light sensitive silver halide emulsion layer containing a color former of the general formula:

where X is a radical selected from the group consisting of the cyano group, carboxylic acyl and esterified carboxyl groups, and Y is an N- heterocyclic nucleus containing an alkyl radical attached to a heterocyclic nitrogen atom which is attached to the acyclic nitrogen atom by the roup, oarboxylic acyl, and. esterifled carboxyl 6. v A photographic element bearing atleast one groups.

8. A method of producing a colored image in a silver halide emulsion which comprises developing the emulsion with an aromatic amino developing agent containing an unsubstituted amino group in the presence of a color former of the 1 general formula:

o=N0 O-CH:X

\N' I a lkyl wherein D constitutes the atoms necessary to complete an azole nucleus and X is a radical selected from the group consisting of the cyano group, carboxylic acyl, and esterified carboxyl groups.

9.. A light sensitive silver halide photographic emulsion containing a color former of the general formula:

wherein D constitutes the atoms necessary to complete an azole nucleus and X is a radical selected from the group consisting of the cyano group, carboxylic acid, and esterified carboxyl groups.

1 0. A photographic color forming developer which comprises an aromatic amino developing compound containing an unsubstituted amino group and a color former of the general formula:.

wherein D' constitutes the atoms necessary to complete a pyridine nucleus, 11 is a number taken from the group consisting of 0 and 1, and X is a radical selected from the group consisting of the cyano group, carboxylic acyl and esterified carboxyl groups.

11. A method of producing a colored image in a silver halide emulsion which comprises developing the emulsion with an aromatic amino developing agent containing an unsubstituted amino group in the presence of a color former of the general formula:

wherein D constitutes the atoms necessary to complete a pyridine nucleus, 11. is a number taken from the group consisting of ,0 and 1, and X is a radical selected from the group consisting of the cyano group, carboxyiie acid and esterified carboxyl groups.

12. A light sensitive silver halide photographic emulsion containing a color former of the general formula:

JOHN DAVID KENDALL. (q RONALD BERNARD COLLINS. 

